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Find video protocols related to scientific articles indexed in Pubmed.
Myricetin Inhibits the Release of Glutamate in Rat Cerebrocortical Nerve Terminals.
J Med Food
PUBLISHED: 10-24-2014
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Abstract The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate the effect and possible mechanism of myricetin, a naturally occurring flavonoid with a neuroprotective profile, on endogenous glutamate release in the nerve terminals (synaptosomes) of the rat cerebral cortex. The release of glutamate was evoked by the K(+) channel blocker 4-aminopyridine (4-AP) and measured by one-line enzyme-coupled fluorometric assay. We also used a membrane potential-sensitive dye to assay the synaptosomal plasma membrane potential, and a Ca(2+) indicator Fura-2 to monitor cytosolic Ca(2+) concentrations ([Ca(2+)]C). Results show that myricetin inhibited 4-AP-evoked glutamate release, and this effect was prevented by chelating extracellular Ca(2+) ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor dl-threo-beta-benzyl-oxyaspartate had no effect on myricetin action. Myricetin did not alter the synaptosomal membrane potential, but decreased 4-AP-induced increases in the cytosolic free Ca(2+) concentration. Furthermore, the myricetin effect on 4-AP-evoked glutamate release was prevented by blocking the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, but not by blocking intracellular Ca(2+) release. These results suggest that myricetin inhibits glutamate release from cerebrocortical synaptosomes by attenuating voltage-dependent Ca(2+) entry. This implies that the inhibition of glutamate release is an important pharmacological activity of myricetin that may play a critical role in the apparent clinical efficacy of this compound.
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A Sticky Weighted Regression Model for Time-Varying Resting State Brain Connectivity Estimation.
IEEE Trans Biomed Eng
PUBLISHED: 09-25-2014
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Despite recent progress on brain connectivity modeling using neuroimaging data such as fMRI, most current approaches assume that brain connectivity networks have time-invariant topology/coefficients. This is clearly problematic as the brain is inherently non-stationary. Here we present a time-varying model to investigate the temporal dynamics of brain connectivity networks. The proposed method allows for abrupt changes in network structure via a fused LASSO scheme, as well as recovery of time-varying networks with smoothly changing coefficients via a weighted regression technique. Simulations demonstrate that the proposed method yields improved accuracy on estimating time-dependent connectivity patterns when compared to a static sparse regression model or a weighted time-varying regression model. When applied to real resting state fMRI data sets from Parkinson's disease (PD) and control subjects, significantly different temporal and spatial patterns were found to be associated with PD. Specifically, PD subjects demonstrated reduced network variability over time, which may be related to impaired cognitive flexibility previously reported in PD. The temporal dynamic properties of brain connectivity in PD subjects may provide insights into brain dynamics associated with PD and may serve as a potential biomarker in future studies.
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Dimensionality Reduction for Hyperspectral Data Based on Class-Aware Tensor Neighborhood Graph and Patch Alignment.
IEEE Trans Neural Netw Learn Syst
PUBLISHED: 09-16-2014
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To take full advantage of hyperspectral information, to avoid data redundancy and to address the curse of dimensionality concern, dimensionality reduction (DR) becomes particularly important to analyze hyperspectral data. Exploring the tensor characteristic of hyperspectral data, a DR algorithm based on class-aware tensor neighborhood graph and patch alignment is proposed here. First, hyperspectral data are represented in the tensor form through a window field to keep the spatial information of each pixel. Second, using a tensor distance criterion, a class-aware tensor neighborhood graph containing discriminating information is obtained. In the third step, employing the patch alignment framework extended to the tensor space, we can obtain global optimal spectral-spatial information. Finally, the solution of the tensor subspace is calculated using an iterative method and low-dimensional projection matrixes for hyperspectral data are obtained accordingly. The proposed method effectively explores the spectral and spatial information in hyperspectral data simultaneously. Experimental results on 3 real hyperspectral datasets show that, compared with some popular vector- and tensor-based DR algorithms, the proposed method can yield better performance with less tensor training samples required.
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P450-catalyzed asymmetric cyclopropanation of electron-deficient olefins under aerobic conditions.
Catal Sci Technol
PUBLISHED: 09-16-2014
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A variant of P450 from Bacillus megaterium five mutations away from wild type is a highly active catalyst for cyclopropanation of a variety of acrylamide and acrylate olefins with ethyl diazoacetate (EDA). The very high rate of reaction enabled by histidine ligation allowed the reaction to be conducted under aerobic conditions. The promiscuity of this catalyst for a variety of substrates containing amides has enabled synthesis of a small library of precursors to levomilnacipran derivatives.
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Targeted enhancement of cortical-hippocampal brain networks and associative memory.
Science
PUBLISHED: 08-30-2014
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The influential notion that the hippocampus supports associative memory by interacting with functionally distinct and distributed brain regions has not been directly tested in humans. We therefore used targeted noninvasive electromagnetic stimulation to modulate human cortical-hippocampal networks and tested effects of this manipulation on memory. Multiple-session stimulation increased functional connectivity among distributed cortical-hippocampal network regions and concomitantly improved associative memory performance. These alterations involved localized long-term plasticity because increases were highly selective to the targeted brain regions, and enhancements of connectivity and associative memory persisted for ~24 hours after stimulation. Targeted cortical-hippocampal networks can thus be enhanced noninvasively, demonstrating their role in associative memory.
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Using (18)F-FLT PET to distinguish between malignant and benign breast lesions with suspicious findings in mammography and breast ultrasound.
Ann Nucl Med
PUBLISHED: 08-20-2014
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To investigate the diagnostic performance of 3'-deoxy-3'-[(18)F]fluorothymidine ((18)F-FLT) PET in women with suspicious breast findings on conventional imaging (mammography and breast ultrasound).
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Anti-viral effect of a compound isolated from Liriope platyphylla against hepatitis B virus in vitro.
Virus Res.
PUBLISHED: 08-19-2014
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The compound LPRP-Et-97543 was isolated from Liriope platyphylla roots and was observed to have potential anti-viral effects in HepG2.2.15 cells against hepatitis B virus (HBV). The antiviral mode was further clarified, and the HBV-transfected Huh7 cells were used as the platform. During viral gene expression, LPRP-Et-97543 treatment had apparent effects on the viral precore/pregenomic and S/preS RNA. Promoter activity analysis demonstrated that LPRP-Et-97543 significantly reduced Core, S, and preS but not X promoter activities. Further examination showed that putative signaling pathways were involved in this inhibitory effect, indicating that NF-?B may serve a putative mediator of HBV gene regulation with LPRP-Et-97543. In addition, the nuclear expression of p65/p50 NF-?B member proteins was attenuated with LPRP-Et-97543 and augmented cytoplasmic I?B? protein levels but without affecting the expression of these proteins in HBV non-transfected cells during treatment. Moreover, LPRP-Et-97543 reduced the binding activity of NF-?B protein to CS1 element of HBV surface gene in a gel retardation analysis and inhibited CS1 containing promoter activity in HBV expressed cells. However, HBV transfection significantly enhances CS1 containing promoter activity without compound treatment in cells. Finally, transfection of the p65 expression plasmid significantly reversed the inhibitory effect of LPRP-Et-97543 on the replicated HBV DNA level in HBV positive cells. In conclusion, this study suggests that the mechanism of HBV inhibition by LPRP-Et-97543 may involve the feedback regulation of viral gene expression and viral DNA replication by HBV viral proteins, which interferes with the NF-?B signaling pathway.
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Effects of SC-560 in Combination with Cisplatin or Taxol on Angiogenesis in Human Ovarian Cancer Xenografts.
Int J Mol Sci
PUBLISHED: 08-17-2014
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This study was designed to evaluate the effect of cyclooxygenase-1 (COX-1) inhibitor, SC-560, combined with cisplatin or taxol, on angiogenesis in human ovarian cancer xenografts. Mice were treated with intraperitoneal (i.p.) injections of SC-560 6 mg/kg/day, i.p. injections of cisplatin 3 mg/kg every other day and i.p. injections of taxol 20 mg/kg once a week for 21 days. Vascular endothelial growth factor (VEGF) mRNA levels were detected by reverse transcription-polymerase chain reaction (RT-PCR); microvessel density (MVD) was determined by immunohistochemistry; and prostaglandin E2 (PGE2) levels were determined using ELISA. Expression levels of VEGF mRNA and MVD in treatment groups were inhibited significantly when compared with the control group (p < 0.05 for all), and SC-560 combined with cisplatin displayed a greater reduction in the expression of VEGF and MVD than SC-560 or cisplatin alone (p < 0.05). SC-560 combined with taxol showed a greater inhibition on VEGF mRNA expression than SC-560 or taxol alone (p < 0.05). The level of PGE2 in treatment groups was significantly reduced when compared with the control group (p < 0.01 for all). These findings may indicate that cisplatin or taxol supplemented by SC-560 in human ovarian cancer xenografts enhances the inhibition effect of cisplatin or taxol alone on angiogenesis.
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Modeling and simulation for medical product development and evaluation: highlights from the FDA-C-Path-ISOP 2013 workshop.
J Pharmacokinet Pharmacodyn
PUBLISHED: 08-11-2014
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Medical-product development has become increasingly challenging and resource-intensive. In 2004, the Food and Drug Administration (FDA) described critical challenges facing medical-product development by establishing the critical path initiative [1]. Priorities identified included the need for improved modeling and simulation tools, further emphasized in FDA's 2011 Strategic Plan for Regulatory Science [Appendix]. In an effort to support and advance model-informed medical-product development (MIMPD), the Critical Path Institute (C-Path) [ www.c-path.org ], FDA, and International Society of Pharmacometrics [ www.go-isop.org ] co-sponsored a workshop in Washington, D.C. on September 26, 2013, to examine integrated approaches to developing and applying model- MIMPD. The workshop brought together an international group of scientists from industry, academia, FDA, and the European Medicines Agency to discuss MIMPD strategies and their applications. A commentary on the proceedings of that workshop is presented here.
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Low yield of chemical shift MRI for characterization of adrenal lesions with high attenuation density on unenhanced CT.
Abdom Imaging
PUBLISHED: 08-07-2014
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To investigate the threshold unenhanced CT density of adrenal nodules at which further evaluation with chemical shift MRI is unlikely to be definitive and therefore not helpful in further characterizing some indeterminate adrenal lesions.
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Predicting fruit fly's sensing rate with insect flight simulations.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 07-21-2014
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Without sensory feedback, flies cannot fly. Exactly how various feedback controls work in insects is a complex puzzle to solve. What do insects measure to stabilize their flight? How often and how fast must insects adjust their wings to remain stable? To gain insights into algorithms used by insects to control their dynamic instability, we develop a simulation tool to study free flight. To stabilize flight, we construct a control algorithm that modulates wing motion based on discrete measurements of the body-pitch orientation. Our simulations give theoretical bounds on both the sensing rate and the delay time between sensing and actuation. Interpreting our findings together with experimental results on fruit flies' reaction time and sensory motor reflexes, we conjecture that fruit flies sense their kinematic states every wing beat to stabilize their flight. We further propose a candidate for such a control involving the fly's haltere and first basalar motor neuron. Although we focus on fruit flies as a case study, the framework for our simulation and discrete control algorithms is applicable to studies of both natural and man-made fliers.
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Cyclooxygenase 2 inhibitor celecoxib inhibits glutamate release by attenuating the PGE2/EP2 pathway in rat cerebral cortex endings.
J. Pharmacol. Exp. Ther.
PUBLISHED: 07-21-2014
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The excitotoxicity caused by excessive glutamate is a critical element in the neuropathology of acute and chronic brain disorders. Therefore, inhibition of glutamate release is a potentially valuable therapeutic strategy for treating these diseases. In this study, we investigated the effect of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor that reduces the level of prostaglandin E2 (PGE2), on endogenous glutamate release in rat cerebral cortex nerve terminals (synaptosomes). Celecoxib substantially inhibited the release of glutamate induced by the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by chelating the extracellular Ca(2+) ions and by the vesicular transporter inhibitor bafilomycin A1. Celecoxib inhibited a 4-AP-induced increase in cytosolic-free Ca(2+) concentration, and the celecoxib-mediated inhibition of glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ?-conotoxin MVIIC. However, celecoxib did not alter 4-AP-mediated depolarization and Na(+) influx. In addition, this glutamate release-inhibiting effect of celecoxib was mediated through the PGE2 subtype 2 receptor (EP2) because it was not observed in the presence of butaprost (an EP2 agonist) or PF04418948 [1-(4-fluorobenzoyl)-3-[[6-methoxy-2-naphthalenyl)methyl]-3-azetidinecarboxylic acid; an EP2 antagonist]. The celecoxib effect on 4-AP-induced glutamate release was prevented by the inhibition or activation of protein kinase A (PKA), and celecoxib decreased the 4-AP-induced phosphorylation of PKA. We also determined that COX-2 and the EP2 receptor are present in presynaptic terminals because they are colocalized with synaptophysin, a presynaptic marker. These results collectively indicate that celecoxib inhibits glutamate release from nerve terminals by reducing voltage-dependent Ca(2+) entry through a signaling cascade involving EP2 and PKA.
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Computed tomography of iatrogenic complications of upper gastrointestinal endoscopy, stenting, and intubation.
Radiol. Clin. North Am.
PUBLISHED: 07-03-2014
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Intraluminal procedures for the gastrointestinal tract range from simple intubation for feeding or bowel decompression to endoscopic procedures including stenting and pancreatobiliary ductal catheterization. Each of these procedures and interventions carries a risk of iatrogenic injury, including bleeding, perforation, infection, adhesions, and obstruction. An understanding of how anatomy and function may predispose to injury, and the distinct patterns of injury, can help the radiologist identify and characterize iatrogenic injury rapidly at computed tomography (CT) imaging. Furthermore, selective use of intravenous or oral CT contrast material can help reveal injury and triage clinical management.
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Some challenges with statistical inference in adaptive designs.
J Biopharm Stat
PUBLISHED: 06-11-2014
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Adaptive designs have generated a great deal of attention to clinical trial communities. The literature contains many statistical methods to deal with added statistical uncertainties concerning the adaptations. Increasingly encountered in regulatory applications are adaptive statistical information designs that allow modification of sample size or related statistical information and adaptive selection designs that allow selection of doses or patient populations during the course of a clinical trial. For adaptive statistical information designs, a few statistical testing methods are mathematically equivalent, as a number of articles have stipulated, but arguably there are large differences in their practical ramifications. We pinpoint some undesirable features of these methods in this work. For adaptive selection designs, the selection based on biomarker data for testing the correlated clinical endpoints may increase statistical uncertainty in terms of type I error probability, and most importantly the increased statistical uncertainty may be impossible to assess.
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Enantioselective imidation of sulfides via enzyme-catalyzed intermolecular nitrogen-atom transfer.
J. Am. Chem. Soc.
PUBLISHED: 06-05-2014
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Engineering enzymes with novel reaction modes promises to expand the applications of biocatalysis in chemical synthesis and will enhance our understanding of how enzymes acquire new functions. The insertion of nitrogen-containing functional groups into unactivated C-H bonds is not catalyzed by known enzymes but was recently demonstrated using engineered variants of cytochrome P450BM3 (CYP102A1) from Bacillus megaterium. Here, we extend this novel P450-catalyzed reaction to include intermolecular insertion of nitrogen into thioethers to form sulfimides. An examination of the reactivity of different P450BM3 variants toward a range of substrates demonstrates that electronic properties of the substrates are important in this novel enzyme-catalyzed reaction. Moreover, amino acid substitutions have a large effect on the rate and stereoselectivity of sulfimidation, demonstrating that the protein plays a key role in determining reactivity and selectivity. These results provide a stepping stone for engineering more complex nitrogen-atom-transfer reactions in P450 enzymes and developing a more comprehensive biocatalytic repertoire.
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Standard error estimation using the EM algorithm for the joint modeling of survival and longitudinal data.
Biostatistics
PUBLISHED: 04-24-2014
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Joint modeling of survival and longitudinal data has been studied extensively in the recent literature. The likelihood approach is one of the most popular estimation methods employed within the joint modeling framework. Typically, the parameters are estimated using maximum likelihood, with computation performed by the expectation maximization (EM) algorithm. However, one drawback of this approach is that standard error (SE) estimates are not automatically produced when using the EM algorithm. Many different procedures have been proposed to obtain the asymptotic covariance matrix for the parameters when the number of parameters is typically small. In the joint modeling context, however, there may be an infinite-dimensional parameter, the baseline hazard function, which greatly complicates the problem, so that the existing methods cannot be readily applied. The profile likelihood and the bootstrap methods overcome the difficulty to some extent; however, they can be computationally intensive. In this paper, we propose two new methods for SE estimation using the EM algorithm that allow for more efficient computation of the SE of a subset of parametric components in a semiparametric or high-dimensional parametric model. The precision and computation time are evaluated through a thorough simulation study. We conclude with an application of our SE estimation method to analyze an HIV clinical trial dataset.
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An EEMD-IVA framework for concurrent multidimensional EEG and unidimensional kinematic data analysis.
IEEE Trans Biomed Eng
PUBLISHED: 04-22-2014
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Joint blind source separation (JBSS) is a means to extract common sources simultaneously found across multiple datasets, e.g., electroencephalogram (EEG) and kinematic data jointly recorded during reaching movements. Existing JBSS approaches are designed to handle multidimensional datasets, yet to our knowledge, there is no existing means to examine common components that may be found across a unidimensional dataset and a multidimensional one. In this paper, we propose a simple, yet effective method to achieve the goal of JBSS when concurrent multidimensional EEG and unidimensional kinematic datasets are available, by combining ensemble empirical mode decomposition (EEMD) with independent vector analysis (IVA). We demonstrate the performance of the proposed method through numerical simulations and application to data collected from reaching movements in Parkinson's disease. The proposed method is a promising JBSS tool for real-world biomedical signal processing applications.
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Synthesis and characterization of silver(I) pyrazolylmethylpyridine complexes and their implementation as metallic silver thin film precursors.
Inorg Chem
PUBLISHED: 04-18-2014
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A series of light- and air-stable silver(I) pyrazolylmethylpyridine complexes [Ag(L(R))]n(BF4)n (L = pyrazolylmethylpyridine; R = H, 1; R = Me, 2; R = i-Pr, 3) and [Ag(L(R))(NO3)]2 (L = pyrazolylmethylpyridine; R = H, 4; R = Me, 5; R = i-Pr, 6) has been synthesized and structurally and spectroscopically characterized. In all of the molecular structures, the pyrazolylmethylpyridine ligands bridge two metal centers, thus giving rise to dinuclear (2, 4, 5, and 6) or polynuclear structures (1 and 3). The role played by the counteranions is also of relevance, because dimeric structures are invariably obtained with NO3(-) (4, 5, and 6), whereas the less-coordinating BF4(-) counteranion affords polymeric structures (1 and 3). Also, through atoms-in-molecules (AIM) analysis of the electron density, an argentophilic Ag···Ag interaction is found in complexes 2 and 4. Thermogravimetric analysis (TGA) shows that the thermolytic properties of the present complexes can be significantly modified by altering the ligand structure and counteranion. These complexes were further investigated as thin silver film precursors by spin-coating solutions, followed by annealing at 310 °C on 52100 steel substrates. The resulting polycrystalline cubic-phase Ag films of ?55 nm thickness exhibit low levels of extraneous element contamination by X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) indicate that film growth proceeds primarily via an island growth (Volmer-Weber) mechanism. Complex 4 was also evaluated as a lubricant additive in ball-on-disk tribological tests. The results of the friction evaluation and wear measurements indicate a significant reduction in wear (? 88%) at optimized Ag complex concentrations with little change in friction. The enhanced wear performance is attributed to facile shearing of Ag metal in the contact region, resulting from thermolysis of the silver complexes, and is confirmed by energy-dispersive X-ray analysis of the resulting wear scars.
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Spontaneous neural fluctuations predict decisions to attend.
J Cogn Neurosci
PUBLISHED: 04-16-2014
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Ongoing variability in neural signaling is an intrinsic property of the brain. Often this variability is considered to be noise and ignored. However, an alternative view is that this variability is fundamental to perception and cognition and may be particularly important in decision-making. Here, we show that a momentary measure of occipital alpha-band power (8-13 Hz) predicts choices about where human participants will focus spatial attention on a trial-by-trial basis. This finding provides evidence for a mechanistic account of decision-making by demonstrating that ongoing neural activity biases voluntary decisions about where to attend within a given moment.
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Brain networks for exploration decisions utilizing distinct modeled information types during contextual learning.
Neuron
PUBLISHED: 04-04-2014
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Exploration permits acquisition of the most relevant information during learning. However, the specific information needed, the influences of this information on decision making, and the relevant neural mechanisms remain poorly understood. We modeled distinct information types available during contextual association learning and used model-based fMRI in conjunction with manipulation of exploratory decision making to identify neural activity associated with information-based decisions. We identified hippocampal-prefrontal contributions to advantageous decisions based on immediately available novel information, distinct from striatal contributions to advantageous decisions based on the sum total available (accumulated) information. Furthermore, network-level interactions among these regions during exploratory decision making were related to learning success. These findings link strategic exploration decisions during learning to quantifiable information and advance understanding of adaptive behavior by identifying the distinct and interactive nature of brain-network contributions to decisions based on distinct information types.
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Application of oxidized starch in bake-only chicken nuggets.
J. Food Sci.
PUBLISHED: 03-11-2014
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There is a need to reduce the fat content in fried foods because of increasing health concerns from consumers. Oxidized starches have been utilized in many coating applications for their adhesion ability. However, it is not known if they perform similarly in bake-only products. This study investigated the application of oxidized starch in bake-only chicken nuggets. Oxidized starches were prepared from 7 starches and analyzed for gelatinization and pasting properties. Chicken nuggets were prepared using batter containing wheat flour, oxidized starch, salt, and leavening agents prior to steaming, oven baking, freezing, and final oven baking for sensory evaluation. All nuggets were analyzed for hardness by a textural analyzer, crispness by an acoustic sound, and sensory characteristics by a trained panel. The oxidation level used in the study did not alter the gelatinization temperature of most starches, but increased the peak pasting viscosity of both types of corn and rice starches and decreased that of tapioca and potato starches. There were slight differences in peak force and acoustic reading between some treatments; however, the differences were not consistent with starch type or amylose content. There was no difference among the treatments as well as between the control with wheat flour and the treatments partially replaced with oxidized starches in all sensory attributes of bake-only nuggets evaluated by the trained panel.
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Dimebon, an antihistamine drug, inhibits glutamate release in rat cerebrocortical nerve terminals.
Eur. J. Pharmacol.
PUBLISHED: 03-05-2014
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The excessive release of glutamate is a critical element in the neuropathology of acute and chronic brain disorders. The purpose of the present study was to investigate the effect and possible mechanism of dimebon, an antihistamine with a neuroprotective profile, on endogenous glutamate release in the nerve terminals (synaptosomes) of the rat cerebral cortex. Dimebon inhibited the release of glutamate that was evoked by exposing the synaptosomes to the K(+) channel blocker 4-aminopyridine, and this effect was prevented by chelating extracellular Ca(2+) ions, and the vesicular transporter inhibitor bafilomycin A1. Dimebon inhibited depolarization-evoked increase in cytosolic free Ca(2+) concentration, and the dimebon-mediated inhibition of glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker ?-conotoxin MVIIC. The inhibitory action of dimebon on glutamate release was not due to its decreasing synaptosomal excitability, because dimebon did not alter the resting synaptosomal membrane potential or 4-aminopyridine-mediated depolarization. Furthemore, the dimebon effect on 4-aminopyridine-evoked glutamate release was prevented by the protein kinase C inhibitor, and dimebon substantially reduced the 4-AP-induced phosphorylation of protein kinase C. However, the dimebon-mediated inhibition of glutamate release was unaffected by the N-methyl-d-aspartate receptor agonist or antagonist. These results suggest that dimebon inhibits glutamate release from rat cortical synaptosomes by suppressing presynaptic voltage-dependent Ca(2+) entry and protein kinase C activity. This implies that the inhibition of glutamate release is an additional pharmacological activity of dimebon that may play a critical role in the apparent clinical efficacy of this compound.
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Diterpene glycosides and polyketides from Xylotumulus gibbisporus.
J. Nat. Prod.
PUBLISHED: 03-05-2014
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Four new tetracyclic diterpene glycosides, namely, sordarins C-F (1-4), and three new ?-lactone polyketides, namely, xylogiblactones A-C (5-7), along with sordarin were isolated from the ethyl acetate extracts of the fermented broths of Xylotumulus gibbisporus YMJ863. The structures of 1-7 were elucidated on the basis of spectroscopic data analyses. The configurations of 1-4 were deduced by NOESY, molecular modeling, and comparison with the literature. The relative configurations of 5-7 were deduced by X-ray crystallographic analysis of 5. Compounds 1-5 and sordarin were evaluated in an antifungal assay using Candida albicans ATCC 18804, C. albicans ATCC MYA-2876, and Saccharomyces cerevisiae ATCC 2345, and only sordarin exhibited significant antifungal activities against these fungal strains, with MIC values of 64.0, 32.0, and 32.0 ?g/mL, respectively. The effect of compounds 1-7 and sordarin on the inhibition of NO production in lipopolysaccharide-activated murine macrophages was also evaluated. Compounds 2 and sordarin inhibited NO production with IC50 values of 327.2±46.6 and 157.1±24.1 ?M, respectively.
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Covert rapid action-memory simulation (CRAMS): A hypothesis of hippocampal-prefrontal interactions for adaptive behavior.
Neurobiol Learn Mem
PUBLISHED: 03-04-2014
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Effective choices generally require memory, yet little is known regarding the cognitive or neural mechanisms that allow memory to influence choices. We outline a new framework proposing that covert memory processing of hippocampus interacts with action-generation processing of prefrontal cortex in order to arrive at optimal, memory-guided choices. Covert, rapid action-memory simulation (CRAMS) is proposed here as a framework for understanding cognitive and/or behavioral choices, whereby prefrontal-hippocampal interactions quickly provide multiple simulations of potential outcomes used to evaluate the set of possible choices. We hypothesize that this CRAMS process is automatic, obligatory, and covert, meaning that many cycles of action-memory simulation occur in response to choice conflict without an individual's necessary intention and generally without awareness of the simulations, leading to adaptive behavior with little perceived effort. CRAMS is thus distinct from influential proposals that adaptive memory-based behavior in humans requires consciously experienced memory-based construction of possible future scenarios and deliberate decisions among possible future constructions. CRAMS provides an account of why hippocampus has been shown to make critical contributions to the short-term control of behavior, and it motivates several new experimental approaches and hypotheses that could be used to better understand the ubiquitous role of prefrontal-hippocampal interactions in situations that require adaptively using memory to guide choices. Importantly, this framework provides a perspective that allows for testing decision-making mechanisms in a manner that translates well across human and nonhuman animal model systems.
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Improved cyclopropanation activity of histidine-ligated cytochrome?P450 enables the enantioselective formal synthesis of levomilnacipran.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 02-26-2014
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Engineering enzymes capable of modes of activation unprecedented in nature will increase the range of industrially important molecules that can be synthesized through biocatalysis. However, low activity for a new function is often a limitation in adopting enzymes for preparative-scale synthesis, reaction with demanding substrates, or when a natural substrate is also present. By mutating the proximal ligand and other key active-site residues of the cytochrome?P450 enzyme from Bacillus megaterium (P450-BM3), a highly active His-ligated variant of P450-BM3 that can be employed for the enantioselective synthesis of the levomilnacipran core was engineered. This enzyme, BM3-Hstar, catalyzes the cyclopropanation of N,N-diethyl-2-phenylacrylamide with an estimated initial rate of over 1000 turnovers per minute and can be used under aerobic conditions. Cyclopropanation activity is highly dependent on the electronic properties of the P450 proximal ligand, which can be used to tune this non-natural enzyme activity.
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A genetically informed, group FMRI connectivity modeling approach: application to schizophrenia.
IEEE Trans Biomed Eng
PUBLISHED: 02-22-2014
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While neuroimaging data can provide valuable phenotypic information to inform genetic studies, the opposite is also true: known genotypes can be used to inform brain connectivity patterns from fMRI data. Here, we propose a framework for genetically informed group brain connectivity modeling. Subjects are first stratified according to their genotypes, and then a group regularized regression model is employed for brain connectivity modeling utilizing the time courses from a priori specified regions of interest (ROIs). With such an approach, each ROI time course is in turn predicted from all other ROI time courses at zero lag using a group regression framework which also incorporates a penalty based on genotypic similarity. Simulations supported such an approach when, as previously studies have indicated to be the case, genetic influences impart connectivity differences across subjects. The proposed method was applied to resting state fMRI data from Schizophrenia and normal control subjects. Genotypes were based on D-amino acid oxidase activator (DAOA) single-nucleotide polymorphisms (SNPs) information. With DAOA SNPs information integrated, the proposed approach was able to more accurately model the diversity in connectivity patterns. Specifically, connectivity with the left putamen, right posterior cingulate, and left middle frontal gyri were found to be jointly modulated by DAOA genotypes and the presence of Schizophrenia. We conclude that the proposed framework represents a multimodal analysis approach for incorporating genotypic variability into brain connectivity analysis directly.
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Classification of EEG signals using a multiple kernel learning support vector machine.
Sensors (Basel)
PUBLISHED: 02-19-2014
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In this study, a multiple kernel learning support vector machine algorithm is proposed for the identification of EEG signals including mental and cognitive tasks, which is a key component in EEG-based brain computer interface (BCI) systems. The presented BCI approach included three stages: (1) a pre-processing step was performed to improve the general signal quality of the EEG; (2) the features were chosen, including wavelet packet entropy and Granger causality, respectively; (3) a multiple kernel learning support vector machine (MKL-SVM) based on a gradient descent optimization algorithm was investigated to classify EEG signals, in which the kernel was defined as a linear combination of polynomial kernels and radial basis function kernels. Experimental results showed that the proposed method provided better classification performance compared with the SVM based on a single kernel. For mental tasks, the average accuracies for 2-class, 3-class, 4-class, and 5-class classifications were 99.20%, 81.25%, 76.76%, and 75.25% respectively. Comparing stroke patients with healthy controls using the proposed algorithm, we achieved the average classification accuracies of 89.24% and 80.33% for 0-back and 1-back tasks respectively. Our results indicate that the proposed approach is promising for implementing human-computer interaction (HCI), especially for mental task classification and identifying suitable brain impairment candidates.
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Cytochrome P450-Catalyzed Insertion of Carbenoids into N-H Bonds.
Chem Sci
PUBLISHED: 02-04-2014
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Expanding nature's catalytic repertoire to include reactions important in synthetic chemistry will open new opportunities for 'green' chemistry and biosynthesis. We demonstrate enzyme-catalyzed insertion of carbenoids into N-H bonds. This type of bond disconnection, which has no counterpart in nature, can be mediated by variants of the cytochrome P450 from Bacillus megaterium. The N-H insertion reaction takes place in water, provides the desired products in 26-83% yield, forms the single addition product exclusively, and does not require slow addition of the diazo component.
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Tea-drinking habit among new university students: associated factors.
Kaohsiung J. Med. Sci.
PUBLISHED: 01-22-2014
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The habit of drinking tea is highly prevalent in Asian countries. The aim of this study was to investigate the prevalence of tea drinking and to explore the correlated factors on tea drinking among young new students in the university, using a validated self-reported questionnaire. This study was carried out with 5936 new students in a university in Taiwan. It comprised a self-administered structured questionnaire, including items related to personal and medical history, and lifestyle habits, using the Pittsburgh Sleep Quality Index (PSQI) and the 12-item Chinese Health Questionnaire (CHQ-12). Anthropometric measurements and laboratory tests were also performed. In total, 2065 (36.1%) students were in the tea-drinking group. Multiple logistic regression analysis showed the following factors were significant predictors of tea drinking: postgraduate students (p < 0.001), coffee drinking (p < 0.001), alcohol drinking (p < 0.001), minor mental morbidity (p = 0.009), poorer sleepers (p = 0.037), higher body mass index (p = 0.004), and sugar-sweetened beverage consumption (p < 0.001). Our data showed that the tea-drinking habit was correlated with higher body mass index, which was contrary to the findings of a previous study. In clinical practice, perhaps we could consider more tea-drinking-related factors when we suggest tea consumption.
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Standardization for subgroup analysis in randomized controlled trials.
J Biopharm Stat
PUBLISHED: 01-08-2014
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Randomized controlled trials (RCTs) emphasize the average or overall effect of a treatment (ATE) on the primary endpoint. Even though the ATE provides the best summary of treatment efficacy, it is of critical importance to know whether the treatment is similarly efficacious in important, predefined subgroups. This is why the RCTs, in addition to the ATE, also present the results of subgroup analysis for preestablished subgroups. Typically, these are marginal subgroup analysis in the sense that treatment effects are estimated in mutually exclusive subgroups defined by only one baseline characteristic at a time (e.g., men versus women, young versus old). Forest plot is a popular graphical approach for displaying the results of subgroup analysis. These plots were originally used in meta-analysis for displaying the treatment effects from independent studies. Treatment effect estimates of different marginal subgroups are, however, not independent. Correlation between the subgrouping variables should be addressed for proper interpretation of forest plots, especially in large effectiveness trials where one of the goals is to address concerns about the generalizability of findings to various populations. Failure to account for the correlation between the subgrouping variables can result in misleading (confounded) interpretations of subgroup effects. Here we present an approach called standardization, a commonly used technique in epidemiology, that allows for valid comparison of subgroup effects depicted in a forest plot. We present simulations results and a subgroup analysis from parallel-group, placebo-controlled randomized trials of antibiotics for acute otitis media.
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A regulatory perspective on essential considerations in design and analysis of subgroups when correctly classified.
J Biopharm Stat
PUBLISHED: 01-08-2014
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This regulatory research provides possible approaches for improvement to conventional subgroup analysis in a fixed design setting. The interaction-to-overall effects ratio is recommended in the planning stage for potential predictors whose prevalence is at most 50% and its observed ratio is recommended in the analysis stage for proper subgroup interpretation if sample size is only planned to target the overall effect size. We illustrate using regulatory examples and underscore the importance of striving for balance between safety and efficacy when considering a regulatory recommendation of a label restricted to a subgroup. A set of decision rules gives guidance for rigorous subgroup-specific conclusions.
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Effect of swimming on the production of aldosterone in rats.
PLoS ONE
PUBLISHED: 01-01-2014
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It has been demonstrated that exercise is one of the stresses known to increase the aldosterone secretion. Both potassium and angiotensin II (Ang II) levels are shown to be correlated with aldosterone production during exercise, but the mechanism is still unclear. In an in vivo study, male rats were catheterized via right jugular vein (RJV), and divided into four groups namely water immersion, swimming, lactate infusion (13 mg/kg/min) and pyruvate infusion (13 mg/kg/min) groups. Each group was treated for 10 min. Blood samples were collected at 0, 10, 15, 30, 60 and 120 min from RJV after administration. In an in vitro study, rat zona glomerulosa (ZG) cells were challenged by lactate (1-10 mM) in the presence or absence of Ang II (10-8 M) for 60 min. The levels of aldosterone in plasma and medium were measured by radioimmunoassay. Cell lysates were analyzed by immunoblotting assay. After exercise and lactate infusion, plasma levels of aldosterone and lactate were significantly higher than those in the control group. Swimming for 10 min significantly increased the plasma Ang II levels in male rats. Administration of lactate plus Ang II significantly increased aldosterone production and enhanced protein expression of steroidogenic acute regulatory protein (StAR) in ZG cells. These results demonstrated that acute exercise led to the increase of both aldosterone and Ang II secretion, which is associated with lactate action on ZG cells and might be dependent on the activity of renin-angiotensin system.
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Tiger beetles pursue prey using a proportional control law with a delay of one half-stride.
J R Soc Interface
PUBLISHED: 01-01-2014
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Tiger beetles are fast diurnal predators capable of chasing prey under closed-loop visual guidance. We investigated this control system using statistical analyses of high-speed digital recordings of beetles chasing a moving prey dummy in a laboratory arena. Correlation analyses reveal that the beetle uses a proportional control law in which the angular position of the prey relative to the beetle's body axis drives the beetle's angular velocity with a delay of about 28 ms. The proportionality coefficient or system gain, 12 s(-1), is just below critical damping. Pursuit simulations using the derived control law predict angular orientation during pursuits with a residual error of about 7°. This is of the same order of magnitude as the oscillation imposed by the beetle's alternating tripod gait, which was not factored into the control law. The system delay of 28 ms equals a half-stride period, i.e. the time between the touch down of alternating tripods. Based on these results, we propose a physical interpretation of the observed control law: to turn towards its prey, the beetle on average exerts a sideways force proportional to the angular position of the prey measured a half-stride earlier.
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Acacetin inhibits glutamate release and prevents kainic acid-induced neurotoxicity in rats.
PLoS ONE
PUBLISHED: 01-01-2014
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An excessive release of glutamate is considered to be a molecular mechanism associated with several neurological diseases that causes neuronal damage. Therefore, searching for compounds that reduce glutamate neurotoxicity is necessary. In this study, the possibility that the natural flavone acacetin derived from the traditional Chinese medicine Clerodendrum inerme (L.) Gaertn is a neuroprotective agent was investigated. The effect of acacetin on endogenous glutamate release in rat hippocampal nerve terminals (synaptosomes) was also investigated. The results indicated that acacetin inhibited depolarization-evoked glutamate release and cytosolic free Ca(2+) concentration ([Ca(2+)]C) in the hippocampal nerve terminals. However, acacetin did not alter synaptosomal membrane potential. Furthermore, the inhibitory effect of acacetin on evoked glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker known as ?-conotoxin MVIIC. In a kainic acid (KA) rat model, an animal model used for excitotoxic neurodegeneration experiments, acacetin (10 or 50 mg/kg) was administrated intraperitoneally to the rats 30 min before the KA (15 mg/kg) intraperitoneal injection, and subsequently induced the attenuation of KA-induced neuronal cell death and microglia activation in the CA3 region of the hippocampus. The present study demonstrates that the natural compound, acacetin, inhibits glutamate release from hippocampal synaptosomes by attenuating voltage-dependent Ca(2+) entry and effectively prevents KA-induced in vivo excitotoxicity. Collectively, these data suggest that acacetin has the therapeutic potential for treating neurological diseases associated with excitotoxicity.
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Protein Kinase D Promotes Airway Epithelial Barrier Dysfunction and Permeability through Down-regulation of Claudin-1.
J. Biol. Chem.
PUBLISHED: 11-21-2013
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At the interface between host and external environment, the airway epithelium serves as a major protective barrier. In the present study we show that protein kinase D (PKD) plays an important role in the formation and integrity of the airway epithelial barrier. Either inhibition of PKD activity or silencing of PKD increased transepithelial electrical resistance (TEER), resulting in a tighter epithelial barrier. Among the three PKD isoforms, PKD3 knockdown was the most efficient one to increase TEER in polarized airway epithelial monolayers. In contrast, overexpression of PKD3 wild type, but not PKD3 kinase-inactive mutant, disrupted the formation of apical intercellular junctions and their reassembly, impaired the development of TEER, and increased paracellular permeability to sodium fluorescein in airway epithelial monolayers. We further found that overexpression of PKD, in particular PKD3, markedly suppressed the mRNA and protein levels of claudin-1 but had only minor effects on the expression of other tight junctional proteins (claudin-3, claudin-4, claudin-5, occludin, and ZO-1) and adherent junctional proteins (E-cadherin and ?-catenin). Immunofluorescence study revealed that claudin-1 level was markedly reduced and almost disappeared from intercellular contacts in PKD3-overexpressed epithelial monolayers and that claudin-4 was also restricted from intercellular contacts and tended to accumulate in the cell cytosolic compartments. Last, we found that claudin-1 knockdown prevented TEER elevation by PKD inhibition or silencing in airway epithelial monolayers. These novel findings indicate that PKD negatively regulates human airway epithelial barrier formation and integrity through down-regulation of claudin-1, which is a key component of tight junctions.
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Biochemical and functional characterization of charge-defined subfractions of high-density lipoprotein from normal adults.
Anal. Chem.
PUBLISHED: 11-13-2013
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High-density lipoprotein (HDL) is regarded as atheroprotective because it provides antioxidant and anti-inflammatory benefits and plays an important role in reverse cholesterol transport. In this paper, we outline a novel methodology for studying the heterogeneity of HDL. Using anion-exchange chromatography, we separated HDL from 6 healthy individuals into five subfractions (H1 through H5) with increasing charge and evaluated the composition and biologic activities of each subfraction. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that apolipoprotein (apo) AI and apoAII were present in all 5 subfractions; apoCI was present only in H1, and apoCIII and apoE were most abundantly present in H4 and H5. HDL-associated antioxidant enzymes such as lecithin-cholesterol acyltransferase, lipoprotein-associated phospholipase A2, and paraoxonase 1 were most abundant in H4 and H5. Lipoprotein isoforms were analyzed in each subfraction by using matrix-assisted laser desorption-time-of-flight mass spectrometry. To quantify other proteins in the HDL subfractions, we used the isobaric tags for the relative and absolute quantitation approach followed by nanoflow liquid chromatography-tandem mass spectrometry analysis. Most antioxidant proteins detected were found in H4 and H5. The ability of each subfraction to induce cholesterol efflux from macrophages increased with increasing HDL electronegativity, with the exception of H5, which promoted the least efflux activity. In conclusion, anion-exchange chromatography is an attractive method for separating HDL into subfractions with distinct lipoprotein compositions and biologic activities. By comparing the properties of these subfractions, it may be possible to uncover HDL-specific proteins that play a role in disease.
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A Three-Step Multimodal Analysis Framework for Modeling Corticomuscular Activity with Application to Parkinsons Disease.
IEEE J Biomed Health Inform
PUBLISHED: 10-04-2013
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Corticomuscular coupling analysis based on multiple data sets such as electroencephalography (EEG) and electromyography (EMG) signals provides a useful tool for understanding human motor control systems. A popular conventional method to assess corticomuscular coupling has been the pairwise magnitude-squared coherence (MSC) between EEG and concomitant EMG recordings. However, there are certain limitations associated with MSC, including the difficulty in robustly assessing group inference, only dealing with two types of data sets simultaneously and the biologically implausible assumption of pair-wise interactions. To overcome such limitations, in this paper, we propose assessing corticomuscular coupling by combining multiset canonical correlation analysis (M-CCA) and joint independent component analysis (jICA). The proposed method takes advantage of M-CCA and jICA to ensure that the extracted components are maximally correlated across multiple data sets and meanwhile statistically independent within each data set. Simulations were performed to illustrate the performance of the proposed method. We also applied the proposed method to concurrent EEG, EMG and behavior data collected in a Parkinsons disease (PD) study. The results reveal highly correlated temporal patterns among the three types of signals and corresponding spatial activation patterns. In addition to the expected motor areas, the corresponding spatial activation patterns demonstrate enhanced occipital connectivity in PD subjects, consistent with previous medical findings.
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Adaptive enrichment with subpopulation selection at interim: Methodologies, applications and design considerations.
Contemp Clin Trials
PUBLISHED: 08-21-2013
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There is a growing interest in pursuing adaptive enrichment for drug development because of its potential to achieve the goal of personalized medicine. There are many versions of adaptive enrichment proposed across many disease indications. Some are exploratory adaptive enrichment and others aim at confirmatory adaptive enrichment. In this paper, we give a brief overview on adaptive enrichment and the methodologies that are growing in statistical literature. A case example is provided to illustrate a regulatory experience that led to drug approval. There were two design elements used for adaptation in this case example: population adaptation and statistical information adaptation. We articulate the challenges in the implementation of a confirmatory adaptive enrichment trial. The challenges include logistic aspects on the appropriate choice of study population for adaptation and the ability to follow the pre-specified rules for statistical information or sample size adaptation. We assess the consistency of treatment effect before and after adaptation using the approach laid out in Wang et al. (2013). We provide the rationales for what would be an appropriate treatment effect estimate for reporting in the drug label. We discuss and articulate design considerations for adaptive enrichment among a dual-composite null hypothesis, a flexible dual-independent null hypothesis and a rigorous dual-independent null hypothesis.
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Risk of dementia after anaesthesia and surgery.
Br J Psychiatry
PUBLISHED: 07-25-2013
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The potential relationship between anaesthesia, surgery and onset of dementia remains elusive.
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Cross-domain object recognition via input-output kernel analysis.
IEEE Trans Image Process
PUBLISHED: 06-08-2013
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It is of great importance to investigate the domain adaptation problem of image object recognition, because now image data is available from a variety of source domains. To understand the changes in data distributions across domains, we study both the input and output kernel spaces for cross-domain learning situations, where most labeled training images are from a source domain and testing images are from a different target domain. To address the feature distribution change issue in the reproducing kernel Hilbert space induced by vector-valued functions, we propose a domain adaptive input-output kernel learning (DA-IOKL) algorithm, which simultaneously learns both the input and output kernels with a discriminative vector-valued decision function by reducing the data mismatch and minimizing the structural error. We also extend the proposed method to the cases of having multiple source domains. We examine two cross-domain object recognition benchmark data sets, and the proposed method consistently outperforms the state-of-the-art domain adaptation and multiple kernel learning methods.
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Anti-Inflammatory Components from the Root of Solanum erianthum.
Int J Mol Sci
PUBLISHED: 05-10-2013
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Two new norsesquiterpenoids, solanerianones A and B (1-2), together with nine known compounds, including four sesquiterpenoids, (-)-solavetivone (3), (+)-anhydro-?-rotunol (4), solafuranone (5), lycifuranone A (6); one alkaloid, N-trans-feruloyltyramine (7); one fatty acid, palmitic acid (8); one phenylalkanoid, acetovanillone (9), and two steroids, ?-sitosterol (10) and stigmasterol (11) were isolated from the n-hexane-soluble part of the roots of Solanum erianthum. Their structures were elucidated on the basis of physical and spectroscopic data analyses. The anti-inflammatory activity of these isolates was monitored by nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage RAW264.7 cells. The cytotoxicity towards human lung squamous carcinoma (CH27), human hepatocellular carcinoma (Hep 3B), human oral squamous carcinoma (HSC-3) and human melanoma (M21) cell lines was also screened by using an MTT assay. Of the compounds tested, 3 exhibited the strongest NO inhibition with the average maximum inhibition (Emax) at 100 ?M and median inhibitory concentration (IC50) values of 98.23% ± 0.08% and 65.54 ± 0.18 ?M, respectively. None of compounds (1-9) was found to possess cytotoxic activity against human cancer cell lines at concentrations up to 30 ?M.
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Wild rice (Zizania palustris L.) prevents atherogenesis in LDL receptor knockout mice.
Atherosclerosis
PUBLISHED: 04-24-2013
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Dietary modifications including healthy eating constitute one of the first line strategies for prevention and treatment of cardiovascular disease (CVD) risk factors including high cholesterol and atherosclerosis. The purpose of the present study was to investigate the potential cardiovascular benefits of wild rice in male and female LDL-receptor-deficient (LDLr-KO) mice.
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Modified toxicity probability interval design: a safer and more reliable method than the 3 + 3 design for practical phase I trials.
J. Clin. Oncol.
PUBLISHED: 04-08-2013
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The 3 + 3 design is the most common choice among clinicians for phase I dose-escalation oncology trials. In recent reviews, more than 95% of phase I trials have been based on the 3 + 3 design. Given that it is intuitive and its implementation does not require a computer program, clinicians can conduct 3 + 3 dose escalations in practice with virtually no logistic cost, and trial protocols based on the 3 + 3 design pass institutional review board and biostatistics reviews quickly. However, the performance of the 3 + 3 design has rarely been compared with model-based designs in simulation studies with matched sample sizes. In the vast majority of statistical literature, the 3 + 3 design has been shown to be inferior in identifying true maximum-tolerated doses (MTDs), although the sample size required by the 3 + 3 design is often orders-of-magnitude smaller than model-based designs. In this article, through comparative simulation studies with matched sample sizes, we demonstrate that the 3 + 3 design has higher risks of exposing patients to toxic doses above the MTD than the modified toxicity probability interval (mTPI) design, a newly developed adaptive method. In addition, compared with the mTPI design, the 3 + 3 design does not yield higher probabilities in identifying the correct MTD, even when the sample size is matched. Given that the mTPI design is equally transparent, costless to implement with free software, and more flexible in practical situations, we highly encourage its adoption in early dose-escalation studies whenever the 3 + 3 design is also considered. We provide free software to allow direct comparisons of the 3 + 3 design with other model-based designs in simulation studies with matched sample sizes.
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A serine-substituted P450 catalyzes highly efficient carbene transfer to olefins in vivo.
Nat. Chem. Biol.
PUBLISHED: 04-04-2013
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Whole-cell catalysts for non-natural chemical reactions will open new routes to sustainable production of chemicals. We designed a cytochrome P411 with unique serine-heme ligation that catalyzes efficient and selective olefin cyclopropanation in intact Escherichia coli cells. The mutation C400S in cytochrome P450(BM3) gives a signature ferrous CO Soret peak at 411 nm, abolishes monooxygenation activity, raises the resting-state Fe(III)-to-Fe(II) reduction potential and substantially improves NAD(P)H-driven activity.
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Panel forum on multiple comparison procedures: a commentary from a complex trial design and analysis plan.
Biom J
PUBLISHED: 04-03-2013
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Motivated by a complex study design aiming at a definitive evidential setting, a panel forum among academia, industry, and US regulatory statistical scientists was held at the 7th International Conference on Multiple Comparison Procedures (MCP) to comment on the multiplicity problem. It is well accepted that studywise or familywise, type I error rate control is the norm for confirmatory trials. But, it is an uncharted territory regarding the criteria beyond a single confirmatory trial. The case example describes a Phase III program consisting of two placebo-controlled multiregional clinical trials identical in design intended to support registration for treatment of a chronic condition in the lung. The case presents a sophisticated multiplicity problem in several levels: four primary endpoints, two doses, two studies, two regions with different regulatory requirements, one major protocol amendment on the original statistical analysis plan, which the panelists had a chance to study before the forum took place. There were differences in professional perspectives among the panelists laid out by sections. Nonetheless, irrespective of the amendment, it may be arguable whether the two studies are poolable for the analysis of two primary endpoints prespecified. How should the study finding be reported in a scientific journal if one health authority approves while the other does not? It is tempting to address the Phase III program level multiplicity motivated by the increasing complexity of the partial hypotheses framework posed that are across studies. A novel thinking of the MCP procedures beyond individual-study level (studywise or familywise as predefined) and across multiple-study level (experimentwise and sometimes programwise) will become an important research problem expected to face with scientific and regulatory challenges.
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Fully biodegradable airway stents using amino alcohol-based poly(ester amide) elastomers.
Adv Healthc Mater
PUBLISHED: 03-25-2013
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Airway stents are often used to maintain patency of the tracheal and bronchial passages in patients suffering from central airway obstruction caused by malignant tumors, scarring, and injury. Like most conventional medical implants, they are designed to perform their functions for a limited period of time, after which surgical removal is often required. Two primary types of airway stents are in general use, metal mesh devices and elastomeric tubes; both are constructed using permanent materials, and must be removed when no longer needed, leading to potential complications. This paper describes the development of process technologies for bioresorbable prototype elastomeric airway stents that would dissolve completely after a predetermined period of time or by an enzymatic triggering mechanism. These airway stents are constructed from biodegradable elastomers with high mechanical strength, flexibility and optical transparency. This work combines microfabrication technology with bioresorbable polymers, with the ultimate goal of a fully biodegradable airway stent ultimately capable of improving patient safety and treatment outcomes.
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Quercetin inhibits depolarization-evoked glutamate release in nerve terminals from rat cerebral cortex.
Neurotoxicology
PUBLISHED: 03-18-2013
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Quercetin, a naturally occurring flavonoid, has been reported to have a neuroprotective profile. An excessive release of glutamate is widely considered to be one of the molecular mechanisms of neuronal damage in several neurological diseases. This study investigated whether quercetin affected glutamate release in rat cerebral cortex nerve terminals (synaptosomes) and explored the possible mechanism. Quercetin inhibited the release of glutamate evoked by the K(+) channel blocker 4-aminopyridine (4-AP), and this effect was prevented by the chelating extracellular Ca(2+) ions. Quercetin decreased the depolarization-induced increase in the cytosolic free Ca(2+) concentration ([Ca(2+)]C), whereas it did not alter 4-AP-mediated depolarization and Na(+) influx. The quercetin-mediated inhibition of glutamate release was prevented by blocking the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, but not by blocking intracellular Ca(2+) release. Combined inhibition of protein kinase C (PKC) and protein kinase A (PKA) also prevented the inhibitory effect of quercetin on evoked glutamate release. Furthermore, quercetin decreased the 4-AP-induced phosphorylation of PKC and PKA. These results suggest that quercetin inhibits glutamate release from rat cortical synaptosomes and this effect is linked to a decrease in presynaptic voltage-dependent Ca(2+) entry and to the suppression of PKC and PKA activity.
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Tanshinone IIA, a constituent of Danshen, inhibits the release of glutamate in rat cerebrocortical nerve terminals.
J Ethnopharmacol
PUBLISHED: 03-11-2013
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Danshen is a commonly used traditional Chinese medicine and has received considerable attention due to their beneficial effects on the health, including prevention of cardiovascular disease, and cancer. Tanshinone IIA, a major active constituent of Danshen, has been reported to have a neuroprotective profile.
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FMEM: Functional mixed effects modeling for the analysis of longitudinal white matter Tract data.
Neuroimage
PUBLISHED: 03-07-2013
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Many longitudinal imaging studies have collected repeated diffusion tensor magnetic resonance imaging data to understand white matter maturation and structural connectivity pattern in normal controls and diseased subjects. There is an urgent demand for the development of statistical methods for the analysis of diffusion properties along fiber tracts and clinical data obtained from longitudinal studies. Jointly analyzing repeated fiber-tract diffusion properties and covariates (e.g., age or gender) raises several major challenges including (i) infinite-dimensional functional response data, (ii) complex spatial-temporal correlation structure, and (iii) complex spatial smoothness. To address these challenges, this article is to develop a functional mixed effects modeling (FMEM) framework to delineate the dynamic changes of diffusion properties along major fiber tracts and their association with a set of covariates of interest and the structure of the variability of these white matter tract properties in various longitudinal studies. Our FMEM consists of a functional mixed effects model for addressing all three challenges, an efficient method for spatially smoothing varying coefficient functions, an estimation method for estimating the spatial-temporal correlation structure, a test procedure with local and global test statistics for testing hypotheses of interest associated with functional response, and a simultaneous confidence band for quantifying the uncertainty in the estimated coefficient functions. Simulated data are used to evaluate the finite sample performance of FMEM and to demonstrate that FMEM significantly outperforms the standard pointwise mixed effects modeling approach. We apply FMEM to study the spatial-temporal dynamics of white-matter fiber tracts in a clinical study of neurodevelopment.
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Effects of diet and host access on fecundity and lifespan in two fruit fly species with different life history patterns.
Physiol. Entomol.
PUBLISHED: 02-27-2013
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The reproductive ability of female tephritids can be limited and prevented by denying access to host plants and restricting the dietary precursors of vitellogenesis. The mechanisms underlying the delayed egg production in each case are initiated by different physiological processes that are anticipated to have dissimilar effects on lifespan and reproductive ability later in life. The egg laying abilities of laboratory reared females of the Mediterranean fruit fly (Ceratitis capitata Wiedmann) and melon fly (Bactrocera cucurbitae Coquillett) from Hawaii are delayed or suppressed by limiting access to host fruits and dietary protein. In each case, this is expected to prevent the loss of lifespan associated with reproduction until protein or hosts are introduced. Two trends are observed in each species: Firstly, access to protein at eclosion leads to a greater probability of survival and higher reproductive ability than if it is delayed, and secondly, that delayed host access reduces lifetime reproductive ability without improving life expectancy. When host access and protein availability are delayed, the rate of reproductive senescence is reduced in the medfly, whereas the rate of reproductive senescence is generally increased in the melon fly. Overall, delaying reproduction lowers the fitness of females by constraining their fecundity for the remainder of the lifespan without extending the lifespan.
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Local anesthetics inhibit glutamate release from rat cerebral cortex synaptosomes.
Synapse
PUBLISHED: 02-23-2013
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Local anesthetics have been widely used for regional anesthesia and the treatment of cardiac arrhythmias. Recent studies have also demonstrated that low-dose systemic local anesthetic infusion has neuroprotective properties. Considering the fact that excessive glutamate release can cause neuronal excitotoxicity, we investigated whether local anesthetics might influence glutamate release from rat cerebral cortex nerve terminals (synaptosomes). Results showed that two commonly used local anesthetics, lidocaine and bupivacaine, exhibited a dose-dependent inhibition of 4-AP-evoked release of glutamate. The effects of lidocaine or bupivacaine on the evoked glutamate release were prevented by the chelation of extracellular Ca²? ions and the vesicular transporter inhibitor bafilomycin A1. However, the glutamate transporter inhibitor dl-threo-beta-benzyl-oxyaspartate did not have any effect on the action of lidocaine or bupivacaine. Both lidocaine and bupivacaine reduced the depolarization-induced increase in [Ca²?]C but did not alter 4-AP-mediated depolarization. Furthermore, the inhibitory effect of lidocaine or bupivacaine on evoked glutamate release was prevented by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but it was not affected by blocking of the ryanodine receptors or the mitochondrial Na?/Ca²? exchange. Inhibition of protein kinase C (PKC) and protein kinase A (PKA) also prevented the action of lidocaine or bupivacaine. These results show that local anesthetics inhibit glutamate release from rat cortical nerve terminals. This effect is linked to a decrease in [Ca²?]C caused by Ca²? entry through presynaptic voltage-dependent Ca²? channels and the suppression of the PKA and PKC signaling cascades.
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An IC-PLS framework for group corticomuscular coupling analysis.
IEEE Trans Biomed Eng
PUBLISHED: 02-20-2013
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Corticomuscular coupling analysis, i.e., examining the relations between simultaneously recorded brain (e.g., electroencephalography--EEG) and muscle (e.g., electro-myography-EMG) signals, is a useful tool for understanding aspects of human motor control. Traditionally, the most popular method to assess corticomuscular coupling has been the pairwise magnitude-squared coherence (MSC) between EEG and concomitant EMG recordings. In this paper, we propose assessing corticomuscular coupling by combining partial least squares (PLS) and independent component analysis (ICA), which addresses many of the limitations of MSC, such as difficulty in robustly assessing group inference and relying on the biologically implausible assumption of pairwise interaction between brain and muscle recordings. In the proposed framework, response relevance and statistical independence are jointly incorporated into a multiobjective optimization function to meaningfully combine the goals of PLS and ICA under the same mathematical umbrella. Simulations, performed under realistic assumptions, illustrated the utility of such an approach. The method was extended to address intersubject variability to robustly discover common corticomuscular coupling patterns across subjects. We then applied the proposed framework to concurrent EEG and EMG data collected in a Parkinsons disease (PD) study. The results from applying the proposed technique revealed temporal components in the EEG and EMG that were significantly correlated with one another. In addition to the expected motor areas, the corresponding spatial activation patterns demonstrated enhanced occipital connectivity in PD subjects, consistent with previous studies suggesting that PD subjects rely excessively on visual information to counteract the deficiency in being able to generate internal commands from their affected basal ganglia.
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Multiple comparisons in complex clinical trial designs.
Biom J
PUBLISHED: 02-18-2013
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Multiple comparisons have drawn a great deal of attention in evaluation of statistical evidence in clinical trials for regulatory applications. As the clinical trial methodology is increasingly more complex to properly take into consideration many practical factors, the multiple testing paradigm widely employed for regulatory applications may not suffice to interpret the results of an individual trial and of multiple trials. In a large outcome trial, an increasing need of studying more than one dose complicates a proper application of multiple comparison procedures. Additional challenges surface when a special endpoint, such as mortality, may need to be tested with multiple clinical trials combined, especially under group sequential designs. Another interesting question is how to study mortality or morbidity endpoints together with symptomatic endpoints in an efficient way, where the former type of endpoints are often studied in only one single trial but the latter type of endpoints are usually studied in at least two independent trials. This article is devoted to discussion of insufficiency of such a widely used paradigm applying only per-trial based multiple comparison procedures and to expand the utility of the procedures to such complex trial designs. A number of viable expanded strategies are stipulated.
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The impacts of using community health volunteers to coach medication safety behaviors among rural elders with chronic illnesses.
Geriatr Nurs
PUBLISHED: 02-12-2013
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It is a challenge for rural health professionals to promote medication safety among older adults taking multiple medications. A volunteer coaching program to promote medication safety among rural elders with chronic illnesses was designed and evaluated. A community-based interventional study randomly assigned 62 rural elders with at least two chronic illnesses to routine care plus volunteer coaching or routine care alone. The volunteer coaching group received a medication safety program, including a coach and reminders by well-trained volunteers, as well as three home visits and five telephone calls over a two-month period. All the subjects received routine medication safety instructions for their chronic illnesses. The program was evaluated using pre- and post-tests of knowledge, attitude and behaviors with regard to medication safety. Results show the volunteer coaching group improved their knowledge of medication safety, but there was no change in attitude after the two-month study period. Moreover, the group demonstrated three improved medication safety behaviors compared to the routine care group. The volunteer coaching program and instructions with pictorial aids can provide a reference for community health professionals who wish to improve the medication safety of chronically ill elders.
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Upregulation of presynaptic proteins and protein kinases associated with enhanced glutamate release from axonal terminals (synaptosomes) of the medial prefrontal cortex in rats with neuropathic pain.
Pain
PUBLISHED: 02-05-2013
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Although nerve injury-induced long-term postsynaptic changes have been investigated, less is known regarding the molecular mechanisms within presynaptic axonal terminals. We investigated the molecular changes in presynaptic nerve terminals underlying chronic pain-induced plastic changes in the medial prefrontal cortex (mPFC). After neuropathic pain was induced by spared nerve injury (SNI) in rats, we assessed the release of the excitatory neurotransmitter glutamate by using in vitro synaptosomal preparations from the mPFC. We also measured the levels of synaptic proteins and protein kinases in synaptosomes using Western blotting. The results showed that unilateral long-term SNI augmented depolarization-evoked glutamate release from synaptosomes of the bilateral mPFC. This result was confirmed by a rapid destaining rate of FM1-43 dye in SNI-operated rats. Unilateral long-term nerve injury also significantly increased synaptic proteins (including synaptophysin, synaptotagmin, synaptobrevin, syntaxin, and 25-kDa synaptosome-associated protein) in synaptosomal fractions from the bilateral mPFC, and ultrastructure images demonstrated increased synaptic vesicular profiles in synaptosomes from SNI animals. Chronic pain upregulated the phosphorylation of endogenous protein kinases, including extracellular signal-regulated kinases 1 and 2 (ERK1/2) and Ca(2+)/calmodulin-dependent kinase II (CaMKII), and synapsin I, the primary presynaptic target of ERK1/2 and CaMKII. Both presynaptic proteins and protein kinases were upregulated after SNI in a time-dependent manner. These results indicate that the long-term neuropathic pain-induced enhancement of glutamate release in the mPFC is linked to increased synaptic vesicle proteins and the activation of the ERK1/2- and CaMKII-synapsin signaling cascade in presynaptic axonal terminals.
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Unsteady aerodynamic forces and torques on falling parallelograms in coupled tumbling-helical motions.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 02-04-2013
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Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card.
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Changes in task-related functional connectivity across multiple spatial scales are related to reading performance.
PLoS ONE
PUBLISHED: 02-02-2013
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Reading requires the interaction of a distributed set of cortical areas whose distinct patterns give rise to a wide range of individual skill. However, the nature of these neural interactions and their relation to reading performance are still poorly understood. Functional connectivity analyses of fMRI data can be used to characterize the nature of interactivity of distributed brain networks, yet most previous studies have focused on connectivity during task-free (i.e., "resting state") conditions. Here, we report new methods for assessing task-related functional connectivity using data-driven graph theoretical methods and describe how large-scale patterns of connectivity relate to individual variability in reading performance among children. We found that connectivity patterns of subjects performing a reading task could be decomposed hierarchically into multiple sub-networks, and we observed stronger long-range interaction between sub-networks in subjects with higher task accuracy. Additionally, we found a network of hub regions known to be critical to reading that displays increased short-range synchronization in higher accuracy subjects. These individual differences in task-related functional connectivity reveal that increased interaction between distant regions, coupled with selective local integration within key regions, is associated with better reading performance. Importantly, we show that task-related neuroimaging data contains far more information than usually extracted via standard univariate analyses--information that can meaningfully relate neural connectivity patterns to cognition and task.
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Bupropion attenuates kainic acid-induced seizures and neuronal cell death in rat hippocampus.
Prog. Neuropsychopharmacol. Biol. Psychiatry
PUBLISHED: 01-23-2013
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Excessive release of glutamate is believed to be a major component of cell damage following excitotoxicity associated with epilepsy. Bupropion, an atypical antidepressant, has been shown to inhibit glutamate release from rat cerebrocortical nerve terminals. The present study was undertaken to investigate whether bupropion has anti-seizure and anti-excitotoxic effects by using a kainic acid (KA) rat seizure model, an animal model for temporal lobe epilepsy and excitotoxic neurodegeneration. Our results show that bupropion (10 or 50mg/kg), administrated intraperitoneally to the rats 30 min before the KA (15 mg/kg) intraperitoneal injection, increased the seizure latency and decreased the seizure score. Bupropion pretreatment attenuated KA-induced neuronal cell death and microglia activation in the CA3 region of the hippocampus. Furthermore, KA-induced c-Fos expression and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in the hippocampus were also reduced by bupropion pretreatment. These results suggest that bupropion has therapeutic potential in the treatment of seizure and other neurological diseases associated with excitotoxicity.
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Ferulic acid suppresses glutamate release through inhibition of voltage-dependent calcium entry in rat cerebrocortical nerve terminals.
J Med Food
PUBLISHED: 01-23-2013
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This study investigated the effects and possible mechanism of ferulic acid, a naturally occurring phenolic compound, on endogenous glutamate release in the nerve terminals of the cerebral cortex in rats. Results show that ferulic acid inhibited the release of glutamate evoked by the K? channel blocker 4-aminopyridine (4-AP). The effect of ferulic acid on the evoked glutamate release was prevented by chelating the extracellular Ca²? ions, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Ferulic acid suppressed the depolarization-induced increase in a cytosolic-free Ca²? concentration, but did not alter 4-AP-mediated depolarization. Furthermore, the effect of ferulic acid on evoked glutamate release was abolished by blocking the Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type) channels, but not by blocking ryanodine receptors or mitochondrial Na?/Ca²? exchange. These results show that ferulic acid inhibits glutamate release from cortical synaptosomes in rats through the suppression of presynaptic voltage-dependent Ca²? entry.
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Knowledge translation of the HELPinKIDS clinical practice guideline for managing childhood vaccination pain: usability and knowledge uptake of educational materials directed to new parents.
BMC Pediatr
PUBLISHED: 01-14-2013
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Although numerous evidence-based and feasible interventions are available to treat pain from childhood vaccine injections, evidence indicates that children are not benefitting from this knowledge. Unrelieved vaccination pain puts children at risk for significant long-term harms including the development of needle fears and subsequent health care avoidance behaviours. Parents report that while they want to mitigate vaccination pain in their children, they lack knowledge about how to do so. An evidence-based clinical practice guideline for managing vaccination pain was recently developed in order to address this knowledge-to-care gap. Educational tools (pamphlet and video) for parents were included to facilitate knowledge transfer at the point of care. The objectives of this study were to evaluate usability and effectiveness in terms of knowledge acquisition from the pamphlet and video in parents of newly born infants.
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A supramolecular approach to combining enzymatic and transition metal catalysis.
Nat Chem
PUBLISHED: 01-06-2013
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The ability of supramolecular host-guest complexes to catalyse organic reactions collaboratively with an enzyme is an important goal in the research and discovery of synthetic enzyme mimics. Herein we present a variety of catalytic tandem reactions that employ esterases, lipases or alcohol dehydrogenases and gold(I) or ruthenium(II) complexes encapsulated in a Ga(4)L(6) tetrahedral supramolecular cluster. The host-guest complexes are tolerated well by the enzymes and, in the case of the gold(I) host-guest complex, show improved reactivity relative to the free cationic guest. We propose that supramolecular encapsulation of organometallic complexes prevents their diffusion into the bulk solution, where they can bind amino-acid residues on the proteins and potentially compromise their activity. Our observations underline the advantages of the supramolecular approach and suggest that encapsulation of reactive complexes may provide a general strategy for carrying out classic organic reactions in the presence of biocatalysts.
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Noisy galvanic vestibular stimulation modulates the amplitude of EEG synchrony patterns.
PLoS ONE
PUBLISHED: 01-01-2013
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Noisy galvanic vestibular stimulation has been associated with numerous cognitive and behavioural effects, such as enhancement of visual memory in healthy individuals, improvement of visual deficits in stroke patients, as well as possibly improvement of motor function in Parkinsons disease; yet, the mechanism of action is unclear. Since Parkinsons and other neuropsychiatric diseases are characterized by maladaptive dynamics of brain rhythms, we investigated whether noisy galvanic vestibular stimulation was associated with measurable changes in EEG oscillatory rhythms within theta (4-7.5 Hz), low alpha (8-10 Hz), high alpha (10.5-12 Hz), beta (13-30 Hz) and gamma (31-50 Hz) bands. We recorded the EEG while simultaneously delivering noisy bilateral, bipolar stimulation at varying intensities of imperceptible currents - at 10, 26, 42, 58, 74 and 90% of sensory threshold - to ten neurologically healthy subjects. Using standard spectral analysis, we investigated the transient aftereffects of noisy stimulation on rhythms. Subsequently, using robust artifact rejection techniques and the Least Absolute Shrinkage Selection Operator regression and cross-validation, we assessed the combinations of channels and power spectral features within each EEG frequency band that were linearly related with stimulus intensity. We show that noisy galvanic vestibular stimulation predominantly leads to a mild suppression of gamma power in lateral regions immediately after stimulation, followed by delayed increase in beta and gamma power in frontal regions approximately 20-25 s after stimulation ceased. Ongoing changes in the power of each oscillatory band throughout frontal, central/parietal, occipital and bilateral electrodes predicted the intensity of galvanic vestibular stimulation in a stimulus-dependent manner, demonstrating linear effects of stimulation on brain rhythms. We propose that modulation of neural oscillations is a potential mechanism for the previously-described cognitive and motor effects of vestibular stimulation, and noisy galvanic vestibular stimulation may provide an additional non-invasive means for neuromodulation of functional brain networks.
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Berberine Inhibits the Release of Glutamate in Nerve Terminals from Rat Cerebral Cortex.
PLoS ONE
PUBLISHED: 01-01-2013
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Berberine, an isoquinoline plant alkaloid, protects neurons against neurotoxicity. An excessive release of glutamate is considered to be one of the molecular mechanisms of neuronal damage in several neurological diseases. In this study, we investigated whether berberine could affect endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes) and explored the possible mechanism. Berberine inhibited the release of glutamate evoked by the K(+) channel blocker 4-aminopyridine (4-AP), and this phenomenon was prevented by the chelating extracellular Ca(2+) ions and the vesicular transporter inhibitor bafilomycin A1, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Inhibition of glutamate release by berberine was not due to it decreasing synaptosomal excitability, because berberine did not alter 4-AP-mediated depolarization. The inhibitory effect of berberine on glutamate release was associated with a reduction in the depolarization-induced increase in cytosolic free Ca(2+) concentration. Involvement of the Cav2.1 (P/Q-type) channels in the berberine action was confirmed by blockade of the berberine-mediated inhibition of glutamate release by the Cav2.1 (P/Q-type) channel blocker ?-agatoxin IVA. In addition, the inhibitory effect of berberine on evoked glutamate release was prevented by the mitogen-activated/extracellular signal-regulated kinase kinase (MEK) inhibitors. Berberine decreased the 4-AP-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synapsin I, the main presynaptic target of ERK; this decrease was also blocked by the MEK inhibition. Moreover, the inhibitory effect of berberine on evoked glutamate release was prevented in nerve terminals from mice lacking synapsin I. Together, these results indicated that berberine inhibits glutamate release from rats cortical synaptosomes, through the suppression of presynaptic Cav2.1 channels and ERK/synapsin I signaling cascade. This finding may provide further understanding of the mode of berberine action in the brain and highlights the therapeutic potential of this compound in the treatment of a wide range of neurological disorders.
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Parkinsons disease rigidity: relation to brain connectivity and motor performance.
Front Neurol
PUBLISHED: 01-01-2013
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Objective: (1) To determine the brain connectivity pattern associated with clinical rigidity scores in Parkinsons disease (PD) and (2) to determine the relation between clinically assessed rigidity and quantitative metrics of motor performance. Background: Rigidity, the resistance to passive movement, is exacerbated in PD by asking the subject to move the contralateral limb, implying that rigidity involves a distributed brain network. Rigidity mainly affects subjects when they attempt to move; yet the relation between clinical rigidity scores and quantitative aspects of motor performance are unknown. Methods: Ten clinically diagnosed PD patients (off-medication) and 10 controls were recruited to perform an fMRI squeeze-bulb tracking task that included both visually guided and internally guided features. The direct functional connectivity between anatomically defined regions of interest was assessed with Dynamic Bayesian Networks (DBNs). Tracking performance was assessed by fitting Linear Dynamical System (LDS) models to the motor performance, and was compared to the clinical rigidity scores. A cross-validated Least Absolute Shrinkage and Selection Operator (LASSO) regression method was used to determine the brain connectivity network that best predicted clinical rigidity scores. Results: The damping ratio of the LDS models significantly correlated with clinical rigidity scores (p?=?0.014). An fMRI connectivity network in subcortical and primary and premotor cortical regions accurately predicted clinical rigidity scores (p?
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Active and passive stabilization of body pitch in insect flight.
J R Soc Interface
PUBLISHED: 01-01-2013
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Flying insects have evolved sophisticated sensory-motor systems, and here we argue that such systems are used to keep upright against intrinsic flight instabilities. We describe a theory that predicts the instability growth rate in body pitch from flapping-wing aerodynamics and reveals two ways of achieving balanced flight: active control with sufficiently rapid reactions and passive stabilization with high body drag. By glueing magnets to fruit flies and perturbing their flight using magnetic impulses, we show that these insects employ active control that is indeed fast relative to the instability. Moreover, we find that fruit flies with their control sensors disabled can keep upright if high-drag fibres are also attached to their bodies, an observation consistent with our prediction for the passive stability condition. Finally, we extend this framework to unify the control strategies used by hovering animals and also furnish criteria for achieving pitch stability in flapping-wing robots.
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Secondary metabolites from the roots of Neolitsea daibuensis and their anti-inflammatory activity.
J. Nat. Prod.
PUBLISHED: 12-07-2011
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Bioassay-guided fractionation of the roots of Neolitsea daibuensis afforded three new ?-carboline alkaloids, daibucarbolines A-C (1-3), three new sesquiterpenoids, daibulactones A and B (4 and 5) and daibuoxide (6), and 20 known compounds. The structures of 1-6 were determined by spectroscopic analysis and single-crystal X-ray diffraction. Daibucarboline A (1), isolinderalactone (7), 7-O-methylnaringenin (8), and prunetin (9) exhibited moderate iNOS inhibitory activity, with IC?? values of 18.41, 0.30, 19.55, and 10.50 ?M, respectively.
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Interactions of excitatory and inhibitory feedback topologies in facilitating pattern separation and retrieval.
Neural Comput
PUBLISHED: 10-24-2011
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Within the brain, the interplay between connectivity patterns of neurons and their spatiotemporal dynamics is believed to be intricately linked to the bases of behavior, such as the process of storing, consolidating, and retrieving memory traces. Memory is believed to be stored in the synaptic patterns of anatomical circuitry in the form of increased connectivity densities within subpopulations of neurons. At the same time, memory recall is thought to correspond to activation of discrete areas of the brain corresponding to those memories. Such regional subpopulations can selectively activate during memory recall or retrieval, signifying the process of accessing a single memory or concept. It has been shown previously that recovery of single memory activity patterns is mediated by global neuromodulation signifying transition into different cognitive states such as sleep or awake exploration. We examine how underlying topology can affect memory awake activation and sleep reactivation when such memories share increasing proportions of neurons. The results show that while single memory activation is diminished with increased overlap, pattern separation can be recovered by offsetting excitatory associations between two memories with targeted and heterogeneous inhibitory feedback. Such findings point to the importance of excitatory-to-inhibitory current balance at both the global and local levels in the context of memory retrieval and replay, and highlight the role of network topology in memory management processes.
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Design, Synthesis, and Biological Evaluation of PKD Inhibitors.
Pharmaceutics
PUBLISHED: 10-12-2011
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Protein kinase D (PKD) belongs to a family of serine/threonine kinases that play an important role in basic cellular processes and are implicated in the pathogenesis of several diseases. Progress in our understanding of the biological functions of PKD has been limited due to the lack of a PKD-specific inhibitor. The benzoxoloazepinolone CID755673 was recently reported as the first potent and kinase-selective inhibitor for this enzyme. For structure-activity analysis purposes, a series of analogs was prepared and their in vitro inhibitory potency evaluated.
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An evidential approach to non-inferiority clinical trials.
Pharm Stat
PUBLISHED: 09-19-2011
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We present likelihood methods for defining the non-inferiority margin and measuring the strength of evidence in non-inferiority trials using the fixed-margin framework. Likelihood methods are used to (1) evaluate and combine the evidence from historical trials to define the non-inferiority margin, (2) assess and report the smallest non-inferiority margin supported by the data, and (3) assess potential violations of the constancy assumption. Data from six aspirin-controlled trials for acute coronary syndrome and data from an active-controlled trial for acute coronary syndrome, Organisation to Assess Strategies for Ischemic Syndromes (OASIS-2) trial, are used for illustration. The likelihood framework offers important theoretical and practical advantages when measuring the strength of evidence in non-inferiority trials. Besides eliminating the influence of sample spaces and prior probabilities on the strength of evidence in the data, the likelihood approach maintains good frequentist properties. Violations of the constancy assumption can be assessed in the likelihood framework when it is appropriate to assume a unifying regression model for trial data and a constant control effect including a control rate parameter and a placebo rate parameter across historical placebo controlled trials and the non-inferiority trial. In situations where the statistical non-inferiority margin is data driven, lower likelihood support interval limits provide plausibly conservative candidate margins.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.